Chromatography is a set of techniques for separating a mixture into its constituents. For instance, in a liquid chromatography application, a pump takes in and delivers a mixture of liquid solvents to a sample manager, where an injected sample awaits its arrival. In an isocratic chromatography application, the composition of the liquid solvents remains unchanged, whereas in a gradient chromatography application, the solvent composition varies over time. The mobile phase, comprised of a sample dissolved in a mixture of solvents, passes to a column, referred to as the stationary phase. By passing the mixture through the column, the various components in the sample separate from each other at different rates and thus elute from the column at different times. A detector receives the elution from the column and produces an output from which the identity and quantity of the analytes may be determined.
During many chromatographic runs, the sample manager may maintain the sample at a low, near-freezing temperature. Critical to the reliability of the outcome of a chromatographic result is the ability to maintain the temperature consistently within the sample chamber (also called a thermal chamber). Because there are temperature differences between the cooling engine and the thermal chamber, the cooling engine needs to run colder than the desired chamber temperature. In addition, invariably there is moisture within the thermal chamber. This moisture condenses on the cooling engine, and will freeze if the cooling engine is at or below the freezing point. Icing of the cooling engine degrades the ability to control chamber temperature, which can have deleterious effects on the results of the chromatographic run.